As a medication method for treating an eye disease, there has been developed a method using a drug delivery system-type contact lens (DDSCL). In such a method, the DDSCL contains a drug and, when being worn, gives controlled release of the drug to an ocular tissue. Since a DDSCL can cover the whole surface of an eye, this method has been understood to be able to deliver a drug at an effective concentration to a tissue in the anterior eye segment such as the cornea and the aqueous humor and to a tissue in the exterior eye segment such as the conjunctiva and tear.
Such a method using a DDSCL, however, is difficult to deliver a drug selectively to a tissue in the posterior eye segment such as the retina, the choroid, the sclera and the vitreous, which are located posterior to the crystalline lens. Given this, there is disclosed a method using an annular (ring-shaped) device having an opening in its center to deliver an ophthalmic drug efficiently to a tissue in the posterior eye segment (see Patent Document 1 below, contents of this document are incorporated herein by reference in its entirety).